Textile treatment compositions suitable for providing fabric softening and static control benefits to laundered fabrics are well-known in the art and have found wide-scale commercial application. Conventionally, rinse-added fabric softening compositions contain, as the active softening component, substantially water-insoluble cationic materials having two long alkyl chains. Typical of such materials are di-stearyl di-methyl ammonium chloride and imidazolinium compounds substituted with two stearyl groups.
Recently, a new class of softening agents has been developed, which possess improved softening abilities. Such compounds, disclosed in EPA 0 199 383, are selected from di-higher alkyl cyclic amines, with the di-tallow imidazolines and ester derivatives thereof being preferred.
Retail fabric softening compositions are typically prepared by dispersion in warm water of a slurry containing the softener material. Making can advantageously be done in a two-step operation, wherein an aqueous dispersion of the softener material is first prepared, and later on further dispersed in water to form the final composition at the desired concentration. The manufacturer has all the reasons to prefer that the first dispersion containing the softener material be as concentrated as possible, in particular obvious economic reasons when the pre-mix has to be shipped before being dispersed in water to form final product, while obviously keeping a pourable and pumpable product for use in further process steps.
However for the new softening materials as well as for the conventional cationic agents mentioned hereinabove, it has proven almost impossible to prepare concentrates containing more than 10% of softening material without encountering intractable problems of product viscosity and stability.
Various solutions have been suggested in the prior art to overcome this problem; illustrations thereof are EPA 406, relating to the incorporation of certain nonionic adjunct softening materials to prepare concentrated dispersions of softener material;
EPA 0,018,039, which relates to hydrocarbons plus soluble cationic or nonionic surfactants in softener concentrates to improve viscosity and stability characteristics;
U.S. Pat. Nos. 4,426,299, and 4,401,578 relating to paraffin, fatty acids and ester estenders for softener concentrates.
However, the various solutions proposed as of yet have not been entirely satisfactory.
It is also generally known for example, in U.S. Pat. No. 3,681,241, that the presence of ionizable salts in softener compositions does help reduce viscosity, but this approach is ineffective in compositions containing more than about 12% of dispersed softener, in as much as the level of ionizable salts necessary to reduce viscosity to any substantial degree has a seriously detrimental effect on product stability.
In addition to the problems related to high concentrations, a further difficulty has appeared in the preparation of softening compositions containing the specific cyclic amines mentioned hereinabove, due to the unstable nature of the materials, the imidazoline ring for example being subject to hydrolysis.
It has appeared that stringent conditions need to be applied if one wants to obtain a stable, concentrated dispersion containing said softening agents in the molten state; such conditions include high temperature, inert atmosphere, absence of moisture, and are therefore difficult and expensive to create, especially upon shipment of the concentrated dispersion.
It has been found that stability problems become even more acute when the said new softening agents are mixed with a quaternary softening agent before being dispersed in water to form the final composition.
There is, therefore, a need for concentrated compositions containing certain cyclic amines softening agents, which show satisfactory viscosity and stability characteristics, especially in the case when the cyclic amine softeners are to be mixed with quaternary softening agents, without requiring stringent conditions, and without requiring the presence of a ionizable salt as electrolyte.
The present invention answers the above need and solves the standing problems of the state of the art.
It is an object of the present invention to provide a process for making stable pourable, pumpable concentrated compositions containing certain cyclic amines softening agents, without needing the adjunction of a ionizable salt as electrolyte.
It is a further object of the present invention to provide a process for making fabric softening compositions containing a cyclic amine softening agent, preferably in combination with a quaternary softening agent.
It is a further object of the present invention to provide concentrated compositions, and fabric softening compositions derivable therefrom, which are made according to the process of the invention.